Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. If you continue browsing the site, you agree to the use of cookies on this website. See our User Agreement and Privacy Policy.

Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. If you continue browsing the site, you agree to the use of cookies on this website. See our Privacy Policy and User Agreement for details.

Folliculitis – inflammation of a follicle or follicles; used ordinarily in reference to hair follicles but sometimes in relation to follicles of other kinds. Impetigo circinate - impetigo of bullous (staphylococcal) type, in which several lesions may become confluent or in which a large bulla ruptures, leaving circinate, raw, often crusted lesions. Confluent yellow crusted papules, vesicles, and crusts Comments: A blistering crusted eruption continued to spread over the face of this healthy 1-year-old boy who was treated with a topical cream by a local quack. He cleared when he was started on an oral antistaphylococcal antibiotic. Bullous impetigo – a staphylococcal skin infection, occurring in infants and children, or rarely in sweaty flexures of adults, and characterized by rapid formation of fragile bullae up to 2 or 3 cm. in diameter, which break early and heal centrally, leaving crusted arcuate or annular erosions. Toxic epidermal necrolysis – an exfoliative skin disease in which erythema rapidly spreads over the entire body, followed by the formation of large flaccid bullae and later by skin that appears scalded and separates from the body in sheets, much as in a second degree burn.

Osteomyelitis – patchy decalcification and periosteal reaction with deposition of new bone. Pneumonia – The radiograph of the child ’s chest shows collapse of the lung on the right and marked displacement of the mediastinum to the left as a result of a pyopneumothorax (a collection of pus and air or gas in the pleural cavity) on the right side.

Introduction of every new class of antimicrobial drug is followed by emergence of resistance. By the 1950s, penicillin-resistant S. aureus were a major threat in hospitals and nurseries. By the 1970s, methicillin-resistant S. aureus had emerged and spread, a phenomenon that encouraged widespread use of vancomycin. Meticillin (INN, BAN) or methicillin (USAN) is a narrow spectrum beta-lactam antibiotic of the penicillin class. It was developed by Beecham in 1959. It was previously used to treat infections caused by susceptible Gram-positive bacteria, particularly beta-lactamase-producing organisms such as Staphylococcus aureus that would otherwise be resistant to most penicillins, but is no longer clinically used. Its role in therapy has been largely replaced by flucloxacillin and dicloxacillin, however the term methicillin-resistant Staphylococcus aureus (MRSA) continues to be used to describe Staphylococcus aureus strains resistant to all penicillins. Methicillin is no longer manufactured because the more stable and similar penicillins such as oxacillin (used for clinical antimicrobial susceptibility testing), flucloxacillin and dicloxacillin are used medically. In the 1990s, vancomycin-resistant enterococci emerged and rapidly spread; most of these organisms are resistant to other traditional first-line antimicrobial drugs. At the end of the century, the first S. aureus strains with reduced susceptibility to vancomycin were documented, prompting concerns that S. aureus fully resistant to vancomycin may be on the horizon. In June 2002 the first case of vancomycin-resistant S. aureus was detected. Early preparations of vancomycin were both nephrotoxic and neurotoxic. Vancomycin preparations today are purer so toxicity is now uncommon but serum levels and renal function have to be monitored and the appropriate dose administered.

Cellulitis is a skin infection caused by bacteria. Normally, your skin helps protect you from infection. But if you have a cut, sore, or insect bite, bacteria can get into the skin and spread to deeper tissues. If it is not treated with antibiotics, the infection can spread to the blood or lymph nodes. This can be deadly. Some people can get cellulitis without having a break in the skin. These include older adults and people who have diabetes or a weak immune system. These people are also more likely to develop dangerous problems from cellulitis. And they are more likely to get cellulitis again.

In the United States, sporadic illnesses caused by B. cereus , C. perfringens , and S. aureus are not reportable (Bennett et al., Clin. Infect. Dis. 2013). Thus estimates of the annual number of illnesses and descriptive epidemiology rely on illnesses that occur in outbreaks. Data reported to a national outbreak surveillance system provides a unique opportunity to examine the epidemiologic and clinical characteristics of outbreaks caused by these pathogens. A foodborne disease outbreak is defined as the occurrence of ≥2 similar illnesses resulting from the ingestion of a common food. Reported errors included allowing foods to remain at room or outdoor temperature for several hours (58%), insufficient time or temperature during reheating (57%), slow cooling of prepared foods (44%), insufficient time or temperature during the initial cooking process (40%), preparing foods more than one-half day in advance of serving (33%), insufficient time or tempterature during hot holding (33%), and inadequate cold holding temperature (22%).

The SE-like proteins either lack emetic activity or have not been tested. Several, including SE-l H, Se-l K, Se-l L, and Se-l Q have been tested and are nonemetic; the remaining SE-l proteins have not been tested. Recent reports of CNS of animal origin (

Current Issues in Foodborne Illness Caused by Staphylococcus aureus

1.
Mark E. Hart, Ph.D.
Division of Microbiology
National Center for Toxicological Research
Food and Drug Administration
Current Issues in Foodborne Illness Caused
by Staphylococcus aureus
The views presented in this presentation do not necessarily reflect
those of the United States Food and Drug Administration.

2.
Presentation Outline
 Introduce you to Staphylococcus aureus
 General characteristics
 Clinical picture
 Antibiotic resistance
 Virulence factors
 Staphylococcus and foodborne illness
 Is it a problem and why?
 Is it an infection or an intoxication?

4.
Staphylococcus
Catalase test
Coagulase test
There are greater than 50
recognized species and
subspecies of
Staphylococcus but three
are of major importance
with respect to human
infections;
S. aureus (Coag+
)
S. epidermidis (Coag-
)
S. saprophyticus (Coag-
)
There are greater than 50
recognized species and
subspecies of
Staphylococcus but three
are of major importance
with respect to human
infections;
S. aureus (Coag+
)
S. epidermidis (Coag-
)
S. saprophyticus (Coag-
)

5.
Too close for comfort!Too close for comfort!
 Estimates suggest thatEstimates suggest that
30 - 40%30 - 40% of the humanof the human
population arepopulation are
asymptomaticallyasymptomatically
colonized at any givencolonized at any given
time on one or more oftime on one or more of
their mucosal surfacestheir mucosal surfaces
 Up toUp to 70%70% of people mayof people may
be transiently colonizedbe transiently colonized
 Anterior nares are theAnterior nares are the
most common site ofmost common site of
colonizationcolonization
 Approximately 90% of
health-care workers
carry the organism
People who are colonized have a higher risk of infection than noncolonized persons.

6.
Predisposing Conditions
 The very young and the very old
 Persons with traumatic or operative
wounds, burns, or other serious skin
lesions
 Persons with chronic debilitating
disorders such as diabetes mellitus,
cancer, or cystic fibrosis
It is therefore, not surprising that serious staphylococcal
disease is most often the result of hospital-acquired
infections.

15.
Objective: To describe the
incidence and distribution
of invasive MRSA disease in
9 US communities and to
estimate the burden of
invasive MRSA infection in
the United States in 2005.
Conclusions: It is
estimated after adjusting
for age, race, and sex to the
US population, that 18,650
in-hospital deaths occurred
in 2005 as a result of
invasive MRSA infections.
By comparison, that same
year, roughly 16,000 people
in the US died from AIDS.
How serious are MRSA infections?
JAMA, October 17, 2007 - Vol. 298, No. 15

21.
Clinical Presentation of CA-MRSAClinical Presentation of CA-MRSA
Cellulitis
75 - 80% of CA-MRSA infections are of the skin and soft tissues

22.
A new “kid in town,”
community-associated (CA) MRSA
• Numerous community outbreaks by predominantly two PFGE
types - USA300 and USA400
• Most notably in
 health care settings in Canada, Native Americans, children in day
care, and a maternity ward in New York (USA400)
 children, correctional facility inmates, participants in sports teams,
men who have sex with men, and military recruits (USA300)
• CA-MRSA is not an archetype to HA-MRSA
• Fatal infections in otherwise healthy individuals (USA400)
 Four pediatric deaths – Minnesota and North Dakota, 1997-1999.
MMWR 1999, 48:707-710
• These isolates all produced Panton-Valentine leukocidin (PVL)
• Genomic analysis of one of these isolates (MW2) revealed 19
novel genes for virulence factors as compared to 5 hospital
strains
• Carry the SCCmec type IVa mobile element
• Susceptible to non β-lactam antibiotics other than
erythromycin

25.
It is estimated (Scallan et al., Emerg. Infect. Dis., 2011)It is estimated (Scallan et al., Emerg. Infect. Dis., 2011)
that of the 48 million foodborne illnesses (1 in 6that of the 48 million foodborne illnesses (1 in 6
Americans) that occur in the United States each year, 9.4Americans) that occur in the United States each year, 9.4
million are caused by known pathogens.million are caused by known pathogens.
Is staphylococcal foodborne illness a problem?Is staphylococcal foodborne illness a problem?
1998 – 2008 surveillance data recorded 6,795 outbreak-1998 – 2008 surveillance data recorded 6,795 outbreak-
associated illnesses resulting in 333 hospitalizations, and 3associated illnesses resulting in 333 hospitalizations, and 3
deaths rankingdeaths ranking S. aureusS. aureus 44thth
behind norovirus,behind norovirus, SalmonellaSalmonella,,
andand Clostridium perfringens.Clostridium perfringens.

26.
Infection or intoxication?
 Staphylococcal food poisoning (SFP) is caused byStaphylococcal food poisoning (SFP) is caused by
preformed toxin, known aspreformed toxin, known as staphylococcal enterotoxinsstaphylococcal enterotoxins
(SE), production in improperly handled foods,(SE), production in improperly handled foods,
therefore, SFP is a toxemia!therefore, SFP is a toxemia!
 Utilizing the MMWR surveillance report (06/28/2013)Utilizing the MMWR surveillance report (06/28/2013)
for 1998 – 2008 which recorded 458 outbreaksfor 1998 – 2008 which recorded 458 outbreaks
consisting of 6,741 confirmed and suspected illnesses,consisting of 6,741 confirmed and suspected illnesses,
 illnesses most often occurred in persons ≥ 20 yearsillnesses most often occurred in persons ≥ 20 years
of age (85%)of age (85%)
 had a median incubation period of 4 hourshad a median incubation period of 4 hours
 diarrhea was commonly reported (≥ 86%)diarrhea was commonly reported (≥ 86%)
 abdominal cramps (median of ≥ 61%) and vomitingabdominal cramps (median of ≥ 61%) and vomiting
(median of 87%)were reported and(median of 87%)were reported and
 median duration of illness was 15 hoursmedian duration of illness was 15 hours
 How much toxin does it take?How much toxin does it take? In humans and
nonhuman primates, 24- to 48-h episodes of retching,
vomiting, and diarrhea every 15 to 30 minutes without
fever resulted when nanogram quantities of SEs were
ingested!

27.
 Meat or poultry dishes were the most commonMeat or poultry dishes were the most common
foods reported accounting for 55% of allfoods reported accounting for 55% of all S. aureusS. aureus
outbreaks; primarily pork of the ham variety.outbreaks; primarily pork of the ham variety.
 Foods implicated were most often prepared in aFoods implicated were most often prepared in a
restaurant or deli (44%)restaurant or deli (44%)
 The most common factors contributing to theThe most common factors contributing to the
occurrence of an outbreak were errors in foodoccurrence of an outbreak were errors in food
processing and preparation and contamination by aprocessing and preparation and contamination by a
food workerfood worker
Infection or intoxication?
(cont)
Reported errors included –
allowing foods to remain at room or outdoor temperature for several
hours (58%)
insufficient time or temperature during reheating (57%)
slow cooling of prepared foods (44%)
insufficient time or temperature during the initial cooking process (40%)
preparing foods more than one-half day in advance of serving (33%)
insufficient time or temperature during hot holding (33%)
and inadequate cold holding temperature (22%)

28.
Characteristics of
staphylococcal enterotoxins (SE)
Molecular sizes ranging from 22 – 29 kDa
Unusually resistant to heat (biologically active
despite boiling for 1 h)
Generally resistant to proteolysis (trypsin and
pepsin) and acids (such as stomach acid) and slightly
resistant to desiccation.
They are secreted by all human-pathogenic S. aureus
Currently S. aureus strains can secret from 1 to 23 of
at least 23 serologically distinct enterotoxins
SEs are defined by emetic activity when ingested by
humans or when given orally to nonhuman primates
Almost all of the SEs are encoded on variable genetic
DNA elements
Note: Schlievert et al., Clin. Infect. Dis. (2008) reports a
strain that expresses all 23!

29.
Over half of theOver half of the
SEs are encodedSEs are encoded
on mobileon mobile
genetic elementsgenetic elements
(plasmid,(plasmid,
bacteriophages,bacteriophages,
transposons, andtransposons, and
pathogenicitypathogenicity
islands)islands)